JPH0232353B2 - TAIKOTAAGETSUTOSHIKISUPATSUTASOCHI - Google Patents

Description

[Detailed Description of the Invention] [Field of Application] The present invention relates to a facing target sputtering apparatus in which a set of targets are faced to each other at a predetermined interval and a thin film is formed on a substrate placed on the side thereof. More specifically, the present invention relates to a facing target sputtering apparatus which can easily adjust the thickness distribution of a thin film to be formed and can form a thin film of uniform thickness over a long period of time, and particularly relates to a facing target sputtering apparatus which is advantageous for forming magnetic thin films.

[Prior Art] The above-mentioned opposed target sputtering apparatus has a pair of targets that serve as cathodes, as is known from "Oyoi Physics" Vol. 48 (1979), No. 6, pages 558 to 559, and Japanese Patent Application Laid-open No. 158380/1983. are provided so that their sputtering surfaces face each other in parallel across a space, and a magnetic field generating means for generating a magnetic field in a direction perpendicular to the sputtering surface is provided, and a film is placed on a substrate placed on the side of the space between the targets. This sputtering device is capable of forming films at high speeds and low temperatures, and is extremely superior in that it can also be applied to magnetic materials.

A technique for forming a uniform film on a wide substrate using the above-mentioned facing target sputtering method is particularly desired from the viewpoint of industrial production such as the manufacture of magnetic recording media.

By the way, as a method for improving the film thickness distribution of the facing target sputtering method, as shown in FIG.
A method has been proposed in which a protrusion Sa protruding inward is provided at the center of two sides of the bent end S of the shield cover of the target T (Japan Society of Applied Magnetics, 32nd Research Meeting Materials P61-70). However, in this method, although the film thickness distribution is improved, since the protrusions are located in front of the target, they often become red hot and melt when bombarded by plasma, resulting in a lack of long-term stability. Furthermore, by providing the protrusions, the discharge voltage for maintaining sputtering increases, making it necessary to increase the sputtering pressure. This causes another problem in that a large amount of sputtering gas is occluded in the film, resulting in unfavorable characteristics of the film formed.

[Object of the invention] The present invention was made in view of the current situation, and
The object of the present invention is to provide a facing target type sputtering device suitable for continuous production in which the thin film distribution can be easily adjusted and the film thickness distribution is stable over a long period of time.

[Structure and Effects of the Invention] The above objects are achieved by the present invention as described below.
That is, the present invention provides the above-mentioned known opposed target type sputtering device, specifically, a seal cover is provided around the target whose sputtering surfaces are arranged parallel to each other across a space, and a seal cover is provided around the target. A facing target is provided with a magnetic field generating means for generating a magnetic field in a direction perpendicular to the sputtering surface on the back surface, and a film is formed on a substrate disposed on the side of the space between the targets so as to face the space. A facing target type sputtering apparatus, characterized in that a plate member is provided so as to form a predetermined pattern of protrusions in front of the front end of the shield cover along at least the periphery of the target on the substrate side. It is.

The above-mentioned present invention was made as follows.

The present inventors have focused on the above-mentioned features of the facing target sputtering apparatus and have studied its application to the manufacture of magnetic recording media. This method is based on the patent application filed in 1983.
A flexible substrate such as a polyester film several hundred meters in length is loaded in the form of a roll into an opposed target sputtering device that combines a wide rectangular target and a transfer roller proposed in No. 163081. A magnetic recording medium is continuously produced by continuously transporting the substrate and forming a predetermined magnetic thin film thereon.

By the way, in the above study, the present inventors discovered the following knowledge, that is, the phenomenon that the thickness distribution in the width direction of the formed thin film shifts in one direction as the sputtering time passes. This is especially noticeable when using the aforementioned rectangular target that is applied to a wide substrate. In many cases, this is not the case. The causes of this include uneven flow of spatter gas,
Slight non-uniformity of the magnetic field for plasma convergence generated from the target surface is considered. That is, it is considered that due to this slight non-uniformity, the distribution of the plasma focused in the opposing target space changes in accordance with the change in the distribution of the magnetic field.

The present invention is based on the above-mentioned knowledge and the principle of the facing target sputtering method, that is, the area of the plasma generated is restricted by the magnetic field for plasma convergence generated in the direction perpendicular to the sputtering surface of the target and the shield cover. This was done based on the fact that it would be eroded.

That is, the present invention focuses on the effect of the shield cover described above and actively utilizes this effect. A plate member is arranged to form a predetermined pattern of protrusions facing in the direction of the substrate, thereby setting the pattern of the plasma region and the diffusion pattern of sputter particles in the direction of the substrate. Therefore, compared to the conventional method of setting a magnetic field pattern by adjusting the arrangement of the magnetic field generating means or the magnetic field strength, this method is extremely simple and has a highly flexible effect.

Moreover, unlike the conventional method described above, the plate-like member of the present invention is arranged from the front end of the seal cover toward the front thereof, so that it does not face the front surface of the target, and therefore the protruding portion is less likely to be damaged by plasma impact. Moreover, the film thickness distribution can be improved without changing the pressure during sputtering, and the problems of the conventional method described above are solved.

The above-mentioned improvement in film thickness distribution according to the present invention is thought to be due to the combination of two effects: restriction of the plasma region by the protrusion and masking effect on the substrate by the protrusion. In order to obtain a particular effect, it is more effective for the plate member to have the same voltage as the shield cover due to the above-mentioned action. That is, it is preferable that it is made of a conductive material and electrically connected to the shield cover.

Furthermore, providing the plate-like member integrally with the shield cover, specifically extending the shield cover so as to form a predetermined pattern of protrusions, has the advantage of simplifying the structure.

In addition, when the target is a magnetic material, in order to avoid changing the magnetic field distribution for plasma focusing even if the sputtered magnetic material is deposited on the protrusion of the plate-like member, it is necessary to use a material that easily passes magnetic flux through the plate-like member. Soft magnetic materials, particularly those with high magnetic permeability, and those with high magnetic flux density are preferred, and soft steel, silicon steel, permalloy, and the like are also preferred since the film thickness distribution does not change during long-term sputtering. In addition, when the target is a magnetic material, a structure in which the shield cover has a tip bent part made of the above-mentioned magnetic material bent toward the target side is advantageous for long-term stable production in combination with the above-mentioned structure. be. In this case, it is advantageous to configure the plate-like member in a predetermined pattern so as to protrude from the bent portion at the tip of the shield cover. The protruding position of the plate member on the bent end portion varies depending on the pattern, the protruding angle, etc., and must be determined experimentally.

In either case, in the case of a rectangular target with a long side in the width direction of the substrate, the pattern of the protrusion is a triangular shape with a wide center and narrow ends, in order to obtain a uniform film thickness over a wide range in the width direction of the substrate. The shape of the film is often used, but it is not particularly limited as long as it is appropriately adjusted based on the pattern of the film thickness distribution.

Furthermore, although the present invention is particularly advantageously applied to a rectangular target that is difficult to adjust the pattern and is long in the width direction of the substrate, it is clear from the above-mentioned gist of the present invention that it is also advantageous for targets having other shapes such as a circle. It is.

Further, although it is clear from the above description that the present invention is particularly effective in forming magnetic thin films, it is also clear that it can be effectively applied to forming thin films other than magnetic thin films.

Hereinafter, details of the present invention will be explained with reference to the drawings.

FIG. 1 is an explanatory view of a facing target type sputtering apparatus according to the present invention, and FIG. 2 is an enlarged view of the target portion thereof.

As is clear from the figure, this device was developed in the above-mentioned JP
It has basically the same structure as the opposed target sputtering device known in Japanese Patent No. 158380.

That is, in the figure, 10 is a vacuum chamber, 20 is an exhaust system consisting of a vacuum pump etc. for evacuating the vacuum chamber 10, and 30 is a system for introducing a predetermined gas into the vacuum chamber 10 to increase the pressure inside the vacuum chamber 10 to 10 ^-1 to 10. This is a gas introduction system that is set to a predetermined gas pressure of approximately 10 ^-4 Torr.

Inside the vacuum chamber 10, target halters 15 and 16 are fixed to the side plates 11 and 12 of the vacuum chamber 10 via insulating members 13 and 14, as shown in the figure, to form a rectangular shape with long sides parallel to the pair of substrates 40. The targets T ₁ and T ₂ are sputtered surfaces T ₁ s,
T ₂ s are arranged so as to face each other in parallel across a space. The targets T ₁ , _{T 2} and the corresponding target holders 15 , ₁₆ are cooled by cooling water via cooling pipes 151 , 161 . Magnets 152 and 162 are targets T ₁ and T ₂
The N and S poles are provided so as to oppose each other, and therefore the magnetic field φ is directed to the targets T 1 and T ₁ as shown in the figure.
Formed only in the direction perpendicular to T ₂ and between targets. Note that 17 and 18 are insulating members 13 and 1
4 and _a shield cover for protecting the target holders 15 and 16 from plasma particles during sputtering and for preventing abnormal discharge on parts other than the _target surface; The tip is a bent portion formed to be bent, and P ₁ and P ₂ are plate-like members of the present invention. Further, MD in the figure indicates the direction of transport of the substrate, that is, the longitudinal direction of the substrate. The direction perpendicular to this is the width direction of the substrate.

By the way, the plate members P ₁ and P ₂ are arranged around the targets T _{1 and} T ₂ so as to form protrusions in a predetermined pattern (a crescent shape in the figure) (see FIG. ₂ ). They are provided on tip bent portions 17a and 18a, which are provided to prevent plasma particles and the like from flying between the shield covers 17 and 18, as described below. The figure shows the target _T1 , but as shown, the target _T1 is the substrate 40.
The bent portion 17a has a constant width W so that the bending width W is constant.
The plate-like material is connected to the spattered surface for a specified period of time (usually several mm to 10
The shield cover 17 is formed by being fixed to the cylindrical portion of the shield cover 17 with the inner periphery thereof located slightly inside the periphery of the target, with an interval of several millimeters between them.
Then, a crescent-shaped plate member _P1 is provided protrudingly on the inside of both sides parallel to the substrate 40 of the tip bent portion 17a, and a crescent-shaped pattern protrusion is formed in the center of each side,
The thickness of the film in the width direction of the substrate 40 is made uniform.
Note that the target _T2 has exactly the same configuration.

Further, a substrate holding means 41 for holding a long substrate 40 on which a magnetic thin film is formed is provided in the vacuum chamber 10 on the sides of the targets T ₁ and T ₂ . The substrate holding means 41 includes feed rolls 41 that hold rolled substrates 40 that are rotatably supported by support brackets (not shown) and parallel to each other's axes.
It consists of three rolls: a, a support roll 41b, and a take-up roll 41c, and targets the substrate 40.
The spattered surface faces the space between T ₁ and T ₂ .
It is arranged so as to be held in a direction substantially perpendicular to T ₁ s and T ₂ s. Therefore, the substrate 40 is the winding roll 4
1c, it is movable in a direction perpendicular to the sputtering surfaces T ₁ s and T ₂ s. Note that the surface temperature of the support roll 41b can be adjusted.

On the other hand, a power supply means 50 consisting of a DC power source for supplying sputtering power has its positive side connected to the ground and its negative side connected to the targets T ₁ and T ₂ , respectively. Therefore, the sputter power from the power supply means 50 is supplied between the anode and the cathode, with the ground as the anode and the targets T ₁ and T ₂ as the cathodes.

In order to protect the substrate 40 during press sputtering, a shutter (not shown) that goes in and out is provided between the substrate 40 and the targets T ₁ and T ₂ .

As described above, the structure is basically the same as that of the above-mentioned Japanese Patent Application Laid-open No. 57-158380, and high-speed low-temperature sputtering is possible as is known. That is, in the space between the targets T ₁ and T ₂ , sputter gas ions, γ electrons emitted by the sputter, etc. are bound by the action of the magnetic field, and a high-density plasma is formed. Therefore, sputtering on the targets T ₁ and T ₂ is promoted, the amount of deposition increases from the space, the deposition rate on the substrate 40 increases, high speed sputtering is possible, and the sputtering on the substrate 40 increases.
Since these are on the sides of the targets T ₁ and T ₂ , low-temperature spatter is also possible.

By the way, as mentioned above, since the crescent-shaped plate members P ₁ and P ₂ are provided at the center on both sides parallel to the substrate 40 of the targets T ₁ and T ₂ , the substrate 40 at the center
Diffusion of the plasma region and sputter particles in the direction is restricted, the film formation rate in the width direction of the substrate 40 is made uniform, and the film thickness of the formed film is made uniform.

The plate members P ₁ and P ₂ are the targets T ₁ and T ₂
Since it does not directly face the surface, stable operation for a long period of time is possible without becoming red hot as in conventional methods.

In addition, the tip bent portions 17a, 18a and the plate-like member
When P ₁ and P ₂ are made of high permeability magnetic material,
Even if a magnetic thin film is formed thereon as described above, the tip bent portion 17a that sets the magnetic field pattern,
The magnetic resistance in the direction of the bending width W of 18a is not affected at all, and therefore, it is
Even when magnetic materials are used for T ₁ and T ₂ , the magnetic field pattern remains stable over a long period of time as set.

The above points will be explained in more detail below.

FIG. 3 shows the tip bent portions 17a, 1 in FIG. 1.
8a is a graph showing the film thickness distribution in the width direction of a comparative example using a conventional device in which plate member P ₁ and P ₂ are not provided, and in which plate member 8a is made of non-magnetic stainless steel.

In this comparative example, the distance between targets T ₁ and T ₂ is 120 mm.
Distance between the substrate side end face of targets T ₁ and T ₂ and the substrate
Under the condition of 20mm, the width in the width direction of the board is 330mm, and the depth
This is a case where a magnetic thin film was continuously formed on a polyethylene terephthalate film with a thickness of 100 μm using targets T ₁ and T ₂ made of permalloy with a rectangle of 130 mm and a thickness of 12 mm.

In the figure, the dotted line indicates the initial stage of operation, and the solid line indicates the initial stage of operation.
The results are shown after 93 hours of continuous operation. As is clear from the figure, the film thickness distribution of the permalloy thin film deposited on the substrate in the target width direction also initially has a film thickness distribution of ±10% with respect to the sputtering effective width, and with respect to the center in the width direction, Although it was a symmetrical shape, after continuous operation, the peak of the film thickness changed in one direction from the center in response to changes in the distribution of magnetic field strength, and the film thickness became thicker in the direction of thickness from the center. It becomes thinner in the thinner direction, and changes to a left-right asymmetrical shape. In the figure, the erosion distribution is the thickness of the target itself, and the film thickness distribution of the permalloy thin film is shown as a percentage with the maximum film thickness as 100%. The maximum erosion depth of the target is 7KW input power.
It was 11.7mm after 93 hours of continuous operation.

FIG. 4 shows the plate-like members P ₁ and P ₂ and the bent end portion 1 in the facing target sputtering device of FIG. 1.
7a and 18a are made of stainless steel, and the plate members P ₁ and P ₂ are shaped like a crescent moon (arc radius: 212.5 mm) with a string length of 180 mm and a width at the midpoint of 20 mm. It is a graph showing the results. In the results of this experiment, a magnetic thin film was continuously formed using the same permanent target targets T ₁ and T ₂ as in the comparative example.

Furthermore, FIG. 5 shows a case where the material of the tip bent portions 17a, 17b and the plate-shaped members P ₁ , P ₂ in the embodiment shown in FIG. These are the implementation results.

The plate-shaped members P ₁ and P ₂ are connected to the bent end portions 17a and 18a.
It can be seen that by attaching the target, the film thickness distribution in the width direction on the substrate immediately after starting use of the target was improved to within ±5% in all cases. In particular, the tip bent portions 17a, 18a and the plate-like member
It can be seen that when P ₁ and P ₂ are made of soft magnetic materials, the film thickness distribution hardly changes even as the target is used.

This is because the target erosion is uniform and the target is effectively utilized. In addition, the magnetic field around the outer periphery of the target is uniform and does not change over a long period of time, and the film thickness distribution in the target width direction is center-symmetric and does not change, allowing stable operation for long periods of time. The uniformity of the film thickness is increased, the uniform area becomes wider, and the product utilization rate improves.

That is, as in the principle of the facing target sputtering method, the plate-like members P ₁ and P ₂ mask the spatter particles coming from the center in the width direction, making them uniform in the width direction, and also reducing the spread of plasma in the center. It is considered that the distribution in the width direction was improved due to the effect of making the erosion distribution of the target more uniform by pushing it back to the center of the target. Furthermore, by forming the tip bent portions 17a, _18a and the plate-shaped members P1, _P2 from a magnetic material with high magnetic permeability, a stronger and more uniform magnetic field can be generated around the outer periphery of the target. it is conceivable that.

In this embodiment, when the target material is copper, which is a non-magnetic material, the tip bent portions 17a, 1
The same results as in FIG. 5 were obtained regardless of the materials of 8a and the plate members P ₁ and P ₂ .

Further, in the embodiment shown in FIG. 5, the thickness of the tip bent portions 17a and 18a made of soft magnetic material is 0.1
Although the speed was changed from m/m to 3 m/m, the effect was the same.

As described above, the present invention is a facing target sputtering apparatus that can be advantageously applied to the stable continuous production of magnetic thin films, such as thin film formation, particularly the production of magnetic recording media, and
It is a useful product with great industrial effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a facing target type sputtering apparatus according to the present invention, a of FIG. 2 is an enlarged plan view of the target section of the apparatus of FIG. 1, and b and c are A--
A', B-B' side sectional view, Figure 3 is a graph showing the film thickness distribution in the substrate width direction of the comparative example, Figure 4 is a graph showing the film thickness distribution in the substrate width direction of the example, and Figure 5 The figure is a graph showing the film thickness distribution in the width direction of the substrate in another embodiment, and FIG. 6 is an explanatory diagram of the target portion of the conventional apparatus. 10: Vacuum chamber, T, T ₁ , T ₂ : Target, S,
17a, 18a: tip bent portion of shield cover,
P ₁ , P ₂ : plate member, 40 : board, 50 : power supply.

Claims (1)

[Claims] 1. A shield cover is provided around a target whose sputtering surfaces face each other in parallel across a space, and a magnetic field is generated on the back surface of the target in a direction perpendicular to the sputtering surface. In the facing target type sputtering apparatus, a magnetic field generating means is provided to form a film on a substrate disposed on the side of the space between the targets so as to face the space. 1. A facing target sputtering device characterized in that a plate member is provided so as to form a predetermined pattern of protrusions forward of the front end of the shield cover along the shield cover. 2. Claim 1, wherein the plate member is conductive and electrically connected to the shield cover.
Opposed target sputtering device as described in . 3. The facing target sputtering apparatus according to claim 1 or 2, wherein the plate member is made of a magnetic material. 4. A facing target sputtering apparatus according to claim 1, 2 or 3, wherein the target has a rectangular shape with long sides parallel to the substrate. 5. The opposed target sputtering apparatus according to claim 4, wherein the plate member is provided so as to form protrusions of the same pattern along both sides parallel to the substrate. 6. The shield cover according to claim 1, 2, 3, 4, or 5, wherein the shield cover has a bent end portion made of a magnetic material and bent toward the target. Opposed target sputtering device. 7. The facing target sputtering device according to claim 6, wherein the plate-like member is provided on the bent end portion of the shield cover. 8. The opposed target sputtering apparatus according to claim 3, 6, or 7, wherein the target is a magnetic material.